1. Field of the Invention
The present invention relates to a sensor device, and a sensor system and an electronic device using the sensor device.
2. Description of the Related Art
In recent years, a proximity sensor of this kind detecting electrostatic capacitance has been proposed as a sensor detecting proximity of an object (e.g., refer to International Publication WO2004/059343). Such a proximity sensor includes a first member to detect proximity and a second member to be a detection object, and can detect the proximity of the second member in a non-contact manner.
However, the proximity sensor disclosed in International Publication WO2004/059343 given above basically detects all objects approaching the first member. Therefore, it is hard to detect only the second member. For instance, if the second member is a tab or a door, the proximity sensor should detect the proximity only of the tab or the door, but the proximity sensor actually detects the proximity of an object other than the tab or the door.
As mentioned above, it is hard for a conventional proximity sensor to accurately detect the proximity only of an object to be detected.